1998 Vol. 15, No. 1
1998, 15(1): 1-6.
Abstract:
Waste vulcanizate powder (RP) was used as an active filler to modify bulk molding compounds (BMC) based on unsaturated polyester. Effects of various factors such as formulation, preparation technologies on toughening results were systematically studied, and a preliminary discussion on toughening mechanism of RP was also made. Results show that the toughening effectiveness is related to the process of pretreatment, amount of stuff, particle size and type of RP used. When monomer/RP1=50/50, particle size=0.28 mm, and amount of stuff=20 phr, impact strength of BMC increases from 5.2 without RP to 11.4 kJ/m2, molding shrinkage decreases from 0.5% to 0.1%, whereas other mechanical properties basically remain unchanged. Analyses of TEM and electronic probe prove the formation of a gradient interpenetrating polymer network (IPN) in the vicinity of phase boundaries between RP and the matrix of BMC. The IPN strengthens combination of interfaces of the two phases, enhancing the impact strength of BMC.
Waste vulcanizate powder (RP) was used as an active filler to modify bulk molding compounds (BMC) based on unsaturated polyester. Effects of various factors such as formulation, preparation technologies on toughening results were systematically studied, and a preliminary discussion on toughening mechanism of RP was also made. Results show that the toughening effectiveness is related to the process of pretreatment, amount of stuff, particle size and type of RP used. When monomer/RP1=50/50, particle size=0.28 mm, and amount of stuff=20 phr, impact strength of BMC increases from 5.2 without RP to 11.4 kJ/m2, molding shrinkage decreases from 0.5% to 0.1%, whereas other mechanical properties basically remain unchanged. Analyses of TEM and electronic probe prove the formation of a gradient interpenetrating polymer network (IPN) in the vicinity of phase boundaries between RP and the matrix of BMC. The IPN strengthens combination of interfaces of the two phases, enhancing the impact strength of BMC.
1998, 15(1): 7-13.
Abstract:
LP-15 polyimide is a new generation Non MDA Polyimide resin. LP-15 polyimide composite exhibited excellent processability, high thermo oxidative stability and mechanical properties at RT and elevated temperature, and thermal cycling resistance. Thus LP-15 polyimide composite offers potential as PMR 15 replacements for use at temperatures up to 280℃.
LP-15 polyimide is a new generation Non MDA Polyimide resin. LP-15 polyimide composite exhibited excellent processability, high thermo oxidative stability and mechanical properties at RT and elevated temperature, and thermal cycling resistance. Thus LP-15 polyimide composite offers potential as PMR 15 replacements for use at temperatures up to 280℃.
1998, 15(1): 14-19.
Abstract:
Mainly explored were two kinds of hybrid composites with different diameter fibers — SiCF-CF/epoxy and BF-CF/epoxy composites. First, analysed was the influence that preparing pressure acted on range and volume content of hybrid fibers. Then, further studied were the hybrid effect of compression and bending properties by using unidirectional small size composites and the contribution that fibers affected the compression and bending properties of materials.
Mainly explored were two kinds of hybrid composites with different diameter fibers — SiCF-CF/epoxy and BF-CF/epoxy composites. First, analysed was the influence that preparing pressure acted on range and volume content of hybrid fibers. Then, further studied were the hybrid effect of compression and bending properties by using unidirectional small size composites and the contribution that fibers affected the compression and bending properties of materials.
1998, 15(1): 20-23.
Abstract:
The composite permeability in the range 1～1000MHz of the conductive and magnetic composite consisting of nickel powder and Ni Zn ferrite was studied. It was found out that, when the nickel content was equal to or less than 47.5%, the composite permeability (μ′,μ″) accorded with the usual composite rules, and that, when equal to or greater than 63.3% and the frequency was in the range 500～1000MHz, an unusual phenomenon appeared, where the real permeability μ′ increased with the frequency increasing, and the imaginary permeability was greater than of the single material in a certain frequency range. This is because the heat from the eddy attenuation of nickel powder in the higher content could change the real and imaginary permeability (μ′,μ″) of Ni Zn ferrite.
The composite permeability in the range 1～1000MHz of the conductive and magnetic composite consisting of nickel powder and Ni Zn ferrite was studied. It was found out that, when the nickel content was equal to or less than 47.5%, the composite permeability (μ′,μ″) accorded with the usual composite rules, and that, when equal to or greater than 63.3% and the frequency was in the range 500～1000MHz, an unusual phenomenon appeared, where the real permeability μ′ increased with the frequency increasing, and the imaginary permeability was greater than of the single material in a certain frequency range. This is because the heat from the eddy attenuation of nickel powder in the higher content could change the real and imaginary permeability (μ′,μ″) of Ni Zn ferrite.
1998, 15(1): 24-29.
Abstract:
Interface phenomena of ceramic Al2O3( α-Al2O3) with liquid HK alloy were investigated experimentally by the sessile drop method. Studies were focused on the wettability, interfacial cohesive strength and interfacial interaction between Al2O3 and HK alloy, and the effects of temperatures and holding time.
Interface phenomena of ceramic Al2O3( α-Al2O3) with liquid HK alloy were investigated experimentally by the sessile drop method. Studies were focused on the wettability, interfacial cohesive strength and interfacial interaction between Al2O3 and HK alloy, and the effects of temperatures and holding time.
1998, 15(1): 30-34.
Abstract:
The chemical compatibility for reinforcements in iron aluminide matrices is analyzed based on the thermodynamic data of binary alloy. This offers the possibility to foretell the chemical reaction of composite systems, so as to reduce experiments work.
The chemical compatibility for reinforcements in iron aluminide matrices is analyzed based on the thermodynamic data of binary alloy. This offers the possibility to foretell the chemical reaction of composite systems, so as to reduce experiments work.
1998, 15(1): 35-38.
Abstract:
Nanocrystalline ZrO2 (Y2O3) powder with different particle sizes was prepared by a boiling hydrolysis method. SiC/ diamond composite toughened with the ZrO2 (Y2O3) was sintered at high temperature (1350℃) and ultra high pressure (5GPa). The phase structure and mechanical properties of the sintered material were investigated by TEM, SEM, XRD and the measurements of impact toughness and G ratio. The results showed that the amount of t ZrO2 in the sintered material increases with boiling hydrolysis time during ZrO2 powder preparation. 100% t ZrO2 was obtained and the particle size distribution is homogeneous on the SiC bonded phase with the boiling hydrolysis time more than 50hr. More than 20vol% of t ZrO2 is transformed to m ZrO2 during the fracture process. The SiC/ diamond composite has a combination property of high impact toughness and high G ratio.
Nanocrystalline ZrO2 (Y2O3) powder with different particle sizes was prepared by a boiling hydrolysis method. SiC/ diamond composite toughened with the ZrO2 (Y2O3) was sintered at high temperature (1350℃) and ultra high pressure (5GPa). The phase structure and mechanical properties of the sintered material were investigated by TEM, SEM, XRD and the measurements of impact toughness and G ratio. The results showed that the amount of t ZrO2 in the sintered material increases with boiling hydrolysis time during ZrO2 powder preparation. 100% t ZrO2 was obtained and the particle size distribution is homogeneous on the SiC bonded phase with the boiling hydrolysis time more than 50hr. More than 20vol% of t ZrO2 is transformed to m ZrO2 during the fracture process. The SiC/ diamond composite has a combination property of high impact toughness and high G ratio.
1998, 15(1): 39-45.
Abstract:
In order to manufacture Al2O3+Ni composite, Al2O3 particles were first coated with TiN by CVD. The homogeneity of the coating layer was characterized by SEM and EDX. The Ti content of the coated powder was analyzed by X ray fluorescence spectrometry. The composite was produced by hot pressing. The densification and mechanical properties of the composite are improved remarkably by applying TiN interlayer. The higher the hot pressing temperature, the more pronounced the favourable effect will be. One reason for these experimental results is that the wettability between TiN and Ni is better than that between Al2O3 and Ni.
In order to manufacture Al2O3+Ni composite, Al2O3 particles were first coated with TiN by CVD. The homogeneity of the coating layer was characterized by SEM and EDX. The Ti content of the coated powder was analyzed by X ray fluorescence spectrometry. The composite was produced by hot pressing. The densification and mechanical properties of the composite are improved remarkably by applying TiN interlayer. The higher the hot pressing temperature, the more pronounced the favourable effect will be. One reason for these experimental results is that the wettability between TiN and Ni is better than that between Al2O3 and Ni.
1998, 15(1): 46-51.
Abstract:
The Effect of rare earth additions (Ce or Y) on the wettability of an Al-Zn-Mg-Cu/Al2O3 system is investigated by vaccum sessile drop method and casting processing in this paper. The results show that rare earth additions into Al-Zn-Mg-Cu alloy can decrease the contact angles effectively and improve interfacial structure with optimum rare earth content being about 0.5wt% for Ce and 0.7wt% for Y. The behaviour of Ce and Y is considered to be the results of interaction between rare earths and the oxide film of the Al alloys or/and α Al2O3 plaque. The rare earth compounds, Ce 2O 3, Al 11 Ce 3, etc, in the interface of Al alloys/Al2O3, have been identified. The suitable combination of rare earths and alloying elements (Mg, Zn, Cu) improves wettability muchmore remarkably than a single rare earth element.
The Effect of rare earth additions (Ce or Y) on the wettability of an Al-Zn-Mg-Cu/Al2O3 system is investigated by vaccum sessile drop method and casting processing in this paper. The results show that rare earth additions into Al-Zn-Mg-Cu alloy can decrease the contact angles effectively and improve interfacial structure with optimum rare earth content being about 0.5wt% for Ce and 0.7wt% for Y. The behaviour of Ce and Y is considered to be the results of interaction between rare earths and the oxide film of the Al alloys or/and α Al2O3 plaque. The rare earth compounds, Ce 2O 3, Al 11 Ce 3, etc, in the interface of Al alloys/Al2O3, have been identified. The suitable combination of rare earths and alloying elements (Mg, Zn, Cu) improves wettability muchmore remarkably than a single rare earth element.
1998, 15(1): 52-55.
Abstract:
The mechanism of in situ TiC/Al composite synthesis with XD method was studied by using DTA, X ray diffraction, TEM and optical microscopy. The results show that Al3Ti phase forms firstly in aluminium matrix and then TiC phase is synthesized through the reaction between Al3Ti phase and C powder. It is thought that Al acts as a catalyst during TiC formation, lowering activation energy and favoring the reaction.
The mechanism of in situ TiC/Al composite synthesis with XD method was studied by using DTA, X ray diffraction, TEM and optical microscopy. The results show that Al3Ti phase forms firstly in aluminium matrix and then TiC phase is synthesized through the reaction between Al3Ti phase and C powder. It is thought that Al acts as a catalyst during TiC formation, lowering activation energy and favoring the reaction.
1998, 15(1): 56-61.
Abstract:
Wear behavior in hybrid composite of 5vol%GrP·10vol%SiCP/ZA27 alloy has been investigated. The wear mechanisms of the hybrid composite under different loads and sliding velocities are mainly discussed and compared with those of SiCP/ZA27 composite and ZA27 alloy. The results indicate that wear resistance of the hybrid composite is better than that of the other two materials. This is because the addition of GrP increases the ability of seizure resistance and delamination resistance. The different changes of worn surface morphologies and worn damaged layers of different materials take place with the increase of loads and sliding velocities, and therefore their transition experiences of wear mechanisms are also different.
Wear behavior in hybrid composite of 5vol%GrP·10vol%SiCP/ZA27 alloy has been investigated. The wear mechanisms of the hybrid composite under different loads and sliding velocities are mainly discussed and compared with those of SiCP/ZA27 composite and ZA27 alloy. The results indicate that wear resistance of the hybrid composite is better than that of the other two materials. This is because the addition of GrP increases the ability of seizure resistance and delamination resistance. The different changes of worn surface morphologies and worn damaged layers of different materials take place with the increase of loads and sliding velocities, and therefore their transition experiences of wear mechanisms are also different.
1998, 15(1): 62-67.
Abstract:
Based on the chemical thermodynamics and kinetics theories, the parent alloy of an in situ reaction system is studied first, and then the TiC-AlN/Al composite is produced by the direct carbonization and nitrogenation of Al-Ti-Mg alloy in the condition of electromagnetic and gas turning mixings. According to the compositions of elements and phases of the kinetics samples taken from the vacuum furnace in different reaction time and measured results of PO2 in the furnace, the effects of furnace atmosphere on the reaction process and the reacted reactants are analyzed.
Based on the chemical thermodynamics and kinetics theories, the parent alloy of an in situ reaction system is studied first, and then the TiC-AlN/Al composite is produced by the direct carbonization and nitrogenation of Al-Ti-Mg alloy in the condition of electromagnetic and gas turning mixings. According to the compositions of elements and phases of the kinetics samples taken from the vacuum furnace in different reaction time and measured results of PO2 in the furnace, the effects of furnace atmosphere on the reaction process and the reacted reactants are analyzed.
1998, 15(1): 68-73.
Abstract:
Al2O3 sol gel was obtained by hydrolysis and polycondensation of chemically modified isopropoxyaluminum Al(OPr) 3 with acetylacetone (AcAcH), performed in the propanol solution with stoichiometric solution of isopropoxyaluninum, and then chemically converted by drying and pyrolysis to form γ-Al2O3 coating on carbon fibers. Further study focused on making the (coated) fiber reinforced aluminum composite prefabrication. The aluminum gel, the coated carbon fiber and the prefabrication were characterized by IR, TG DTA, XRD, SEM, etc . The results show that γ-Al2O3 coating prevents the harmful reaction between C/Al and penetration of oxygen molecule effectively. After the coating treatment, oxidation resistance of carbon fibers is enhanced, the moistability between the fibers and melting aluminum is greatly improved, and the tensile strength of C/Al prefabrication is heightened.
Al2O3 sol gel was obtained by hydrolysis and polycondensation of chemically modified isopropoxyaluminum Al(OPr) 3 with acetylacetone (AcAcH), performed in the propanol solution with stoichiometric solution of isopropoxyaluninum, and then chemically converted by drying and pyrolysis to form γ-Al2O3 coating on carbon fibers. Further study focused on making the (coated) fiber reinforced aluminum composite prefabrication. The aluminum gel, the coated carbon fiber and the prefabrication were characterized by IR, TG DTA, XRD, SEM, etc . The results show that γ-Al2O3 coating prevents the harmful reaction between C/Al and penetration of oxygen molecule effectively. After the coating treatment, oxidation resistance of carbon fibers is enhanced, the moistability between the fibers and melting aluminum is greatly improved, and the tensile strength of C/Al prefabrication is heightened.
1998, 15(1): 74-77.
Abstract:
The present paper reports the authors first finding concerning the method of controlling a slight interfacial reaction in SiCP/6061Al composite fabricated by squeeze casting. Reaction mechanism and reaction effect on the Youngs modulus of the composite were studied. The results indicate that the interfacial reaction products are isolated small particles of MgAl2O4. The principal supply of oxygen in reaction is the residual thin SiO2 layer around the as received SiCParticles. The existence of reaction product found in the study has a beneficial effect on the Youngs modulus enhancement of the composite.
The present paper reports the authors first finding concerning the method of controlling a slight interfacial reaction in SiCP/6061Al composite fabricated by squeeze casting. Reaction mechanism and reaction effect on the Youngs modulus of the composite were studied. The results indicate that the interfacial reaction products are isolated small particles of MgAl2O4. The principal supply of oxygen in reaction is the residual thin SiO2 layer around the as received SiCParticles. The existence of reaction product found in the study has a beneficial effect on the Youngs modulus enhancement of the composite.
1998, 15(1): 78-82.
Abstract:
The properties and wear characteristic of Al2O3 particles reinforced copper composite by electrodeposit have been investigated, and their hardness and wearability were tested in the range of 0.5 to 5.0μm particles size and 4 to 16vol% content. The results show that the coating hardness increases linearly with Al2O3 content, and the coating with large Al2O3 particles is slightly harder than the one with smaller particles. The content and the size of Al2O3 particles have great effects on the wearability and wear mechanism of the composites.
The properties and wear characteristic of Al2O3 particles reinforced copper composite by electrodeposit have been investigated, and their hardness and wearability were tested in the range of 0.5 to 5.0μm particles size and 4 to 16vol% content. The results show that the coating hardness increases linearly with Al2O3 content, and the coating with large Al2O3 particles is slightly harder than the one with smaller particles. The content and the size of Al2O3 particles have great effects on the wearability and wear mechanism of the composites.
1998, 15(1): 83-87.
Abstract:
C/Cu composites with different interface bonding strength have been fabricated by adding Sn,Ni or Fe element to the copper matrix. The effect of interface bonding strength on the thermal expansion behavior of C/Cu composites has been investigated. Its influence on the contracting behavior (occurring at the cooling stage) and the residual strain values of composites has also been studied in this paper.
C/Cu composites with different interface bonding strength have been fabricated by adding Sn,Ni or Fe element to the copper matrix. The effect of interface bonding strength on the thermal expansion behavior of C/Cu composites has been investigated. Its influence on the contracting behavior (occurring at the cooling stage) and the residual strain values of composites has also been studied in this paper.
1998, 15(1): 88-92.
Abstract:
The damping property of 2024Al/SiCP(17.6% V f)metal matrix composites produced by spray codeposition is reported in this paper. The property is about 142% higher than that of 2024 alloy produced by spray deposition and nearly 184% higher than that of 2024 produced by conventional casting.
The damping property of 2024Al/SiCP(17.6% V f)metal matrix composites produced by spray codeposition is reported in this paper. The property is about 142% higher than that of 2024 alloy produced by spray deposition and nearly 184% higher than that of 2024 produced by conventional casting.
1998, 15(1): 93-100.
Abstract:
The fatigue behaviour of the Al2O3·SiO2 fibre reinforced aluminum matrix composites produced by the squeeze casting method was investigated. The fatigue crack initiation and propagation were observed by SEM. It is found that the initiation of fatigue cracks is originated from different areas. The fatigue crack growth in the form of linking main cracks with the voids, formed at the tip of cracks, or in a discontinuous manner follows a fibre and shots concentrated path. During the fatigue process, the formation of the main crack expends most of the whole fatigue life, and once the main crack forms, the crack propagates rapidly and fractures immediately. It is believed that Al2O3·SiO2f /ZL108 composites show a characteristic of brittle fracture macroscopically, but the matrix of the composites still shows more ductility in microscopic characteristics.
The fatigue behaviour of the Al2O3·SiO2 fibre reinforced aluminum matrix composites produced by the squeeze casting method was investigated. The fatigue crack initiation and propagation were observed by SEM. It is found that the initiation of fatigue cracks is originated from different areas. The fatigue crack growth in the form of linking main cracks with the voids, formed at the tip of cracks, or in a discontinuous manner follows a fibre and shots concentrated path. During the fatigue process, the formation of the main crack expends most of the whole fatigue life, and once the main crack forms, the crack propagates rapidly and fractures immediately. It is believed that Al2O3·SiO2f /ZL108 composites show a characteristic of brittle fracture macroscopically, but the matrix of the composites still shows more ductility in microscopic characteristics.
1998, 15(1): 101-107.
Abstract:
Wear of diamond alloy composite segments under various conditions is observed through Alot of experiments on the basis of previous researches on segment wear. Influences of granites, diamonds and metal bonds on wear characteristics of diamond segments have been discussed. In the end, wear characteristics of diamonds during grinding and polishing granites have been analyzed and measures to deal with the problems have also been put forward.
Wear of diamond alloy composite segments under various conditions is observed through Alot of experiments on the basis of previous researches on segment wear. Influences of granites, diamonds and metal bonds on wear characteristics of diamond segments have been discussed. In the end, wear characteristics of diamonds during grinding and polishing granites have been analyzed and measures to deal with the problems have also been put forward.
1998, 15(1): 108-111.
Abstract:
A computational method — microelement method which establishes the immediate relation between the microstructure and macroresponse in composite materials is discussed. The method, firstly, divides the composite structure into a set of macroelements, then analyzes the microstructure, and translates the variables of the microstructure into variables of nodes for calculation. In this method, any arbitrary pattern of microstructure and any tiny change will be reflected in macrovariables without increasing the degrees of freedom.
A computational method — microelement method which establishes the immediate relation between the microstructure and macroresponse in composite materials is discussed. The method, firstly, divides the composite structure into a set of macroelements, then analyzes the microstructure, and translates the variables of the microstructure into variables of nodes for calculation. In this method, any arbitrary pattern of microstructure and any tiny change will be reflected in macrovariables without increasing the degrees of freedom.
1998, 15(1): 112-115.
Abstract:
The image displaying method, showing damage in fibre optic network embedded in composite materials, is studied. And a corresponding detection system has been made. By digitally processing the image which carries all the information exported by the network, damage in composite materials can be quantitatively detected and directly displayed. The results of the impact damage tests proved that the fibre optic image system has many advantages compared with ordinary photo electric detecting systems.
The image displaying method, showing damage in fibre optic network embedded in composite materials, is studied. And a corresponding detection system has been made. By digitally processing the image which carries all the information exported by the network, damage in composite materials can be quantitatively detected and directly displayed. The results of the impact damage tests proved that the fibre optic image system has many advantages compared with ordinary photo electric detecting systems.
1998, 15(1): 116-120.
Abstract:
The design of joint area is the key to composite structures, and the determination of joint load is the critical part of a multi fastener joint problem. Based on the displacement method of FE theory, a method for determination of joint load distribution is suggested in this paper which is based on the finite super element. The difficulty of determining composite P δ curve by experiment is avoided, and at the same time this method possesses higher computational efficiency. There are no any limitations on the joint geometrical shape, dimensions, arrangement of joints, external applied loads, boundary conditions, etc. in this method. The accuracy and efficiency of this method are verified by tests and typical examples. At last, the load distribution in many cases is studied and some important conclusions have been obtained.
The design of joint area is the key to composite structures, and the determination of joint load is the critical part of a multi fastener joint problem. Based on the displacement method of FE theory, a method for determination of joint load distribution is suggested in this paper which is based on the finite super element. The difficulty of determining composite P δ curve by experiment is avoided, and at the same time this method possesses higher computational efficiency. There are no any limitations on the joint geometrical shape, dimensions, arrangement of joints, external applied loads, boundary conditions, etc. in this method. The accuracy and efficiency of this method are verified by tests and typical examples. At last, the load distribution in many cases is studied and some important conclusions have been obtained.
1998, 15(1): 121-125.
Abstract:
The methodology of fracture mechanics based on continuous crack growth was applied to the investigation of the microscopic damage evolution and toughness calculation for fiber composites. The multi mode failure processes were simulated by means of the finite element technique. The fracture energy and loading phase of the interface were taken as the essential microstructural parameters and the toughening mechanisms were discussed. A toughness design principle of fiber composites was developed.
The methodology of fracture mechanics based on continuous crack growth was applied to the investigation of the microscopic damage evolution and toughness calculation for fiber composites. The multi mode failure processes were simulated by means of the finite element technique. The fracture energy and loading phase of the interface were taken as the essential microstructural parameters and the toughening mechanisms were discussed. A toughness design principle of fiber composites was developed.
1998, 15(1): 126-130.
Abstract:
If piezoelectrical material has been used as one of the layers of composite material laminate, the laminate becomes so called piezoelectrical adaptive one, which has not only the load bearing capacity, but also the measuring and actuating capacity. In this paper, the actuating effect of piezoelectrical element is changed for an equivalent mechanical load, and the piezoelectrical adaptive laminate is analyzed with the classical laminate theory. The theoretical results satisfy the experimental ones very much.
If piezoelectrical material has been used as one of the layers of composite material laminate, the laminate becomes so called piezoelectrical adaptive one, which has not only the load bearing capacity, but also the measuring and actuating capacity. In this paper, the actuating effect of piezoelectrical element is changed for an equivalent mechanical load, and the piezoelectrical adaptive laminate is analyzed with the classical laminate theory. The theoretical results satisfy the experimental ones very much.
1998, 15(1): 131-137.
Abstract:
A nonlinear finite element based on the total Lagrangian incremental formulation of a two dimensional anisotropic medium is developed, and its application in the geometrical nonlinear buckling and postbuckling analysis of stiffened layered composite shell is demonstrated via example problems under the combination of mechanical loading and hygrothermal loading. The finite element based on the Sander's shell theory with transverse shear strains is also presented. The tangential stiffness matrices of rectangle shell finite element, the beam and curved beam, the equivalent hygrothermal force vector, and the method of analysis of buckling and postbuckling are given. Finally, several example problems are illustrated by the FORTRAN Programme.
A nonlinear finite element based on the total Lagrangian incremental formulation of a two dimensional anisotropic medium is developed, and its application in the geometrical nonlinear buckling and postbuckling analysis of stiffened layered composite shell is demonstrated via example problems under the combination of mechanical loading and hygrothermal loading. The finite element based on the Sander's shell theory with transverse shear strains is also presented. The tangential stiffness matrices of rectangle shell finite element, the beam and curved beam, the equivalent hygrothermal force vector, and the method of analysis of buckling and postbuckling are given. Finally, several example problems are illustrated by the FORTRAN Programme.
